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11: Polygonum thunbergii Sieb. et Zucc. (Polygonaceae)
Author(s) -
KAWANO SHOICHI
Publication year - 2008
Publication title -
plant species biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 36
eISSN - 1442-1984
pISSN - 0913-557X
DOI - 10.1111/j.1442-1984.2008.00226.x
Subject(s) - polygonaceae , biology , polygonum , achene , botany , biological dispersal , inflorescence , wetland , plant reproductive morphology , ecology , population , demography , sociology
The life‐history characteristics and demography of Polygonum thunbergii Sieb. et Zucc. (Polygonaceae) are described here. This is a typical annual species of the Polygonaceae, extending widely over wetlands in the lowlands of the Japanese Islands and in north‐eastern Asia. A unique feature of P. thunbergii is that each individual plant possesses two reproductive systems, that is, chasmogamy and cleistogamy. Chasmogamous flowers are borne on the cymose inflorescences with 10–20 flowers, reddish to pinkish in color, that attract various insects. A variety of pollinators visit the flowers, including horse flies and small butterflies, which obviously guarantees a certain degree of outbreeding among different individuals. The achenes produced are ovoid, trigonous, yellowish‐brown and dull in color and do not possess any specific seed dispersal mechanisms. Several cleistogamous flowers are produced at the tip of underground runners elongated from the base of the stems into the soil layers. The reproductive strategy of P. thunbergii is unique as an annual and the two reproductive systems (chasmogamy and cleistogamy [geocarpy]) allow populations to persist in unstable changing environments, such as the flood plains of rivers and wetlands developed at the margins of ponds or lakes.